When a man refuses to apologize to a woman for something wrong he has done, he could put her at risk of a heart attack, say scientists.
A study found that women who are starved of an apology for rude or hurtful behaviour suffer an increase in blood pressure, which can raise the risk of a heart attack or stroke.
The research also showed that those who hear a well timed "sorry" calm down more quickly, with their blood pressure returning to normal 20 percent faster.
On the other hand, a man's blood pressure takes 20 percent longer to recover after an apology - suggesting men become more worked up after hearing an admission of guilt.
Scientists at the University of Massachusetts Medical School in Worcester, US, measured the diastolic blood pressure of 29 men and 59 women throughout the experiment.
Both groups were asked individually to complete a maths test in five minutes. They were interrupted three times during the test and told angrily to hurry up.
At the end of the test, they were told: "You're obviously not good enough."
Two minutes later, researchers apologised for their rudeness to half of the men and women.
The women who received an apology calmed down faster, while the men became more agitated.
"Results indicate that there are potentially healthy benefits to forgiveness and apology," the Telegraph quoted one of the researchers as saying.
Diastolic blood pressure, a measure of pressure in the blood between heartbeats, can increase the chances of stroke or heart attacks if it remains high.